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What is Porokeratosis?

Medically Reviewed by Dan Brennan, MD on April 27, 2021

Porokeratosis is a skin condition which appears as raised brown bumps that may expand into scaly patches. They often have raised rings around the spots. Porokeratosis is not contagious, but it may be passed down through genetics.

Understanding Porokeratosis

Porokeratosis is most commonly found among children and young adults. At first, you may notice a small patch of brown bumps. This patch grows in size, and the bumps may become raised with a ring around the outside of each spot.

The exact cause of porokeratosis is not known, but genetic factors and having a weak immune system may put you at a greater risk for the condition. Sunlight, UV rays, and other radiation worsen the condition.

Types of Porokeratosis

There are several varieties of porokeratosis. The two most common types of this skin condition are porokeratosis of Mibelli and disseminated superficial actinic porokeratosis (DSAP). Less common types are porokeratosis palmaris et plantaris disseminate and linear porokeratosis. 

Porokeratosis of Mibelli. This type of porokeratosis develops on your skin, and may also affect other tissue in your body. It can even turn into skin cancer, with 8% of patients suffering from the condition developing cancer on the patches. You’re at a greater risk for skin cancer with larger patches of porokeratosis mibelli and infections that last longer.

Keep in mind that while porokeratosis of Mibelli may appear on several parts of your body, it doesn’t spread via contact. It is not a contagious disease. If you have the condition, you may pass a predisposition for it down to your children.

Disseminated superficial actinic porokeratosis (DSAP). Similar to porokeratosis of Mibelli, this condition appears as patches of brown, scaly spots. DSAP is more common on your arms and legs but may also affect skin that is damaged from the sun. DSAP is caused by an ultra-sensitivity to sunlight.

‌A majority of people with DSAP inherit it from family genes. However, it is possible to develop the condition if you have a weak immune system. While porokeratosis of Mibelli is more common in children and young adults, DSAP is more common in older adults. It doesn’t appear until sun damage occurs, so it is also more prevalent in people with fair skin. As the condition worsens, it can feel dry, itchy, and irritated.

Risks of Porokeratosis

If porokeratosis is left untreated, the condition may worsen. The patches grow larger and leave you at risk for skin cancer. Additionally, the condition may cause more irritation over time.

‌If you notice patches of brown bumps that appear to grow and spread, talk to your doctor. While the skin condition may be harmless, it’s better to get a professional opinion. You should also talk to your doctor before trying any home or over-the-counter medications.

Porokeratosis or Ringworm?

Porokeratosis spots often have a rough, raised border that may look like ringworm. The rashes are different because ringworm is caused by the fungus tinea corporis and is contagious, unlike porokeratosis. Ringworm is also slightly different in appearance. The raised ring is usually red, and the center of the spot is either the same color as your flesh or slightly paler. If you’re not sure how to distinguish between the two skin conditions, talk to your doctor.‌

You can easily treat ringworm at home with an over-the-counter antifungal cream. If you use an antifungal cream on porokeratosis, you won’t see the results you expect. Instead, your condition may continue to worsen.  

Treatment for Porokeratosis

Porokeratosis of Mibelli. Your doctor may suggest monitoring its growth over time. It is important to limit sun and UV exposure to the affected areas of your skin. Your doctor may prescribe Imiquimod cream, 5-fluorouracil cream, or retinoid cream because they are shown to improve skin affected by porokeratosis.‌

Your exact treatment depends on your other health conditions and the severity of your porokeratosis. Surgery is a last resort if your condition doesn’t improve with other treatments.

Disseminated superficial actinic porokeratosis (DSAP). DSAP is considered a pre-cancerous skin growth, although it rarely turns into cancer. Your doctor will monitor the spots and may take a sample of skin to biopsy if the spots change too much. The best course of action is preventing further sun damage. Cover affected areas of skin when you are in the sun and wear strong sunscreens.

The same creams that work on porokeratosis of Mibelli also work on DSAP. Cryosurgery and photodynamic therapy are also treatment options, although they offered varying results.

WebMD Medical Reference

Sources

SOURCES:
American Osteopathic College of Dermatology: “DISSEMINATED SUPERFICIAL ACTINIC POROKERATOSIS.”

Genetic and Rare Diseases Information Center: “Porokeratosis of Mibelli.”

Indian Dermatology Online Journal: “Porokeratosis - Head to toe: An unusual presentation.”

Mayo Clinic: “Ringworm (body).”

The MalaCards human disease database: “Porokeratosis (DSAP).”

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